Technical Abstract:
In aquaculture, the development and use of vaccines is now making rapid progress to achieve its full potential as an effective disease prevention tool. Currently, USDA, APHIS, CVB licenses 17 fish vaccines of which 2 are modified live and 14 are killed vaccines. The objective of vaccination is to provide a strong immune response to an administered antigen able to provide acquired long-term protection against a pathogen. To achieve this objective, either a killed or modified live vaccine needs to be developed and licensed for use in fresh or marine water aquaculture. The type of immunity needed, antibody and/or cell-mediated against, a particular pathogen is among the deciding factors in the development of a vaccine. The life stage of the fish, production practices and the duration of protection are among the other deciding factors. Injection is the least cost effective in terms of labor and time. Killed vaccines administered by bath immersion have been partially successful. Modified live vaccines may be administered by bath immersion to large numbers of fish (fry and/or eggs) which is a more cost effective method of mass vaccination in both labor and time. Consequently, future advances include oral (fed) delivery of vaccines, immersion, development of additional modified live, subunit, DNA, multivalent vaccines and improved vaccine adjuvant and immunostimulant(s). This paper will present examples of new channel catfish and tilapia vaccines to examine some of the advantages and disadvantages in the development and use of fish vaccines.